Have a mouth as sharp as a dagger, but a heart as soft as tofu. ~ Chinese proverb
Soy is native to east Asia. Myth has the fabled Emperor Shénnóng of China proclaim in ~2800 bce that 5 plants were sacred: soybeans, rice, wheat, barley, and millet.
Becoming a treasured bean takes time. Soybeans were domesticated in China 5000–3500 bce.
Soy is among the richest foods in phytoestrogens: plant compounds which mimic estrogenic effects in animals. Plants employ phytoestrogens to fight fungi and other nuisances.
Phytoestrogens present a health hazard to humans, particularly infants and youngsters. They can reduce fertility and may raise the risk of cancer.
Fermentation greatly reduces the level of phytoestrogens in soy. The fermentation process is essential to unlocking the nutrition potential of soy and defusing its health hazards. Fermented soy is healthy in moderation: providing protein, calcium, iron, manganese, phosphorus, and phytonutrients.
Tofu is not a fermented soy food; but miso, nattō, and tempeh are.
The soy to positively avoid is that found in processed foods, made with soy protein isolate and preservatives. These products are commonly marketed as vegan substitutes for meat and dairy products but are not healthy.